The long term objective is to characterize key functionalities of the epithelial cells of the larval mosquito gut as these cellular functions influence and regulate the anionic basis of alkalinization of the gut lumen. A detailed understanding of how gut epithelial cells produce the remarkable and biologically unique pH extremes (i.e. >10.5) that drive the digestive process will provide new avenues for the development of environmentally safe and specific larvacides. Two specific gene families have been targeted as they have central roles in anion production and transport in the gut alkalinization process: carbonic anhydrases and transmembrane anion transporters. This project will produce molecular and physiological characterizations of members of these two gene families. Their distributions in the tissue and specific roles in larval mosquito gut alkalinization will be defined. Specific cellular phenotypes throughout the gut will be defined and the role of each in the alkalinization process assessed. AIM 1 will examine the expression of multiple carbonic anhydrases. AIM 2 will define and characterize members of the anion transporter gene family. AIM 3 will define the cellular distributions of carbonic anhydrases and anion transporters in the gut and as functions of larval development. AIM 4 will produce a global analysis of gene expression in the specific functional domains of the larval mosquito gut identifying key functionalities which define the gut domains. AIM 5 will bring the localization of specific gene products together with physiological measurements of the activity of individual cells to produce a cell-specific and spatial analysis of anion dynamics in the gut epithelium. As mosquitoes are the number one threat to human health world wide and recognized as potential agents for bioterrorism, the development of new strategies for control based on unique aspects of their biology (i.e. gut alkalinization) has important potential.